A rolling bearing with a rotation sensor is sometimes used for supporting a rotation shaft in a variety of devices to detect its rotational speed (number of revolutions). This rolling bearing with a rotation sensor has an annular magnetic encoder alternately polarized in different magnetic poles in the circumferential direction and mounted on one of the inner and outer races of the bearing that is rotatable. A sensor housing incorporating a magnetic sensor for detecting the change of the magnetic flux when the encoder rotates is mounted on the other stationary race to detect the rotation of the rotating race. A circuit board for processing the output of the magnetic sensor is often mounted in the sensor housing.
In many cases, such a sensor housing for a rolling bearing with a rotation sensor is made of a resin, and mounted on the stationary race through a metal outer ring. Among those resin sensor housings, some have a tubular duct formed integrally with the housing so that output cables of the magnetic sensor, which are connected to the circuit board in the sensor housing and drawn out of the housing, will not be damaged or broken by shearing or other forces (e.g. JP 2002-213472A).
In the rolling bearing with the rotation sensor (a magnetic sensor) described in JP 2002-213472A, the output cables of the magnetic sensor can be protected from damage. But the output cables connected to the circuit board inside the sensor housing have to be mounted to extend outside through the tubular duct, and the mounting process is a laborious process.